Generator regulator



April 29, 1952 R. J. cAsslDY GENERATOR REGULATOR 'Filed Nov. 17, 1949ENG/Ne- Smc/f ess/SM05 E .Vw w

im J pm Patented Apr. 29, 1952 UNITED STATES iAT-ENT FFICE GENERATORREGULATOR Application November 17, 1949, Serial No. 127,812

2 Claims. (Cl..322-28) VThis invention relates to the regulation of analternating rcurrent generator kdriven at variable speed, for example,by the propelling engine of an automotive vehicle and operable tosupply, through ya rectifier, current for exciting the generator field,for charging a storage battery Vand. for other devices operating ondirect current. By regulating the current supplied to the generatorlield windings, the D. C. output voltage of the rectifier is maintainedsubstantially constant over a relative wide range oi operating speeds.

An object of the invention is to enable the generator to put out an A.C. voltage adequate for useful purposes even at speeds lower thanpossible heretofore thereby avoiding the necessity of using a moreexpensive generator in order to obtain that adequate voltage at lowspeeds. For example, an A. C. generator already available vior use onpassenger busses can be enabled by the use of the present invention ltosupply A. C. voltage adequate for illumination by fluorescent lamps atlower speed than heretofore possible. in the disclosed embodiment of theinvention, this obj ct is accomplished by so modifying the excitationoi' the magnet ycoil of the voltage regulater that, when alternatingcurrent from Ythe generator is used by the lamps, the voltage which theregulator is set to maintain is increased in consequence of vwhich theregulating resistance is reducedand field current and A. C. voltage arehigher than they would be otherwise.

Further objects and advantages of the present invention will be apparentfrom the following description1eierence being had to the accompanyingwherein a preferred embodiment of the present invention ,is clearlyshown.

lin the drawing:

li'ig. l is a wiring .diagram of the invention.

Figs. 2-5 are charts issued in explaining its operation.

Referring to Fig. l, an A. C. generator driven by the vehicle engine VEhas 'a non-rotating armature AIii and a rotary iield excited by coil II. The terminals ci the generator are connected by a transformer i2 andconventional accessories with nuorescent lamps I3 having individualcontrol switches Isy and are connected with the input terminals oi arectifier lll, one D. C. terminal of which is grounded and the otherwith wire I5 connectible by a manually'controlled switch I5 with astorage battery Il.

The D. C. output Voltage is regulated by a carbon pile regulator havinga stack 2i? `connected between wire Vl5 and the -iield coil il and urgedinto low resistance status by a spring -il and having `a control coil 22for opposing the action of the spring order to maintain a desired D. C.voltage.

The action of the regulator is modiiied, when creased to r1.

ftain the lamps 13. rz were then existing, generator A. C. voltagevsulicient to maintain the lamps I 3 could be produced at -a somewhatlower speed.

2 a lamp I3 is turned on by means comprising a W-heatstone bridge 23having intermediate terminals connected with coil 22 and having endVterminal-s connected with rectifier is and having one leg connected asshown with the output termina-ls of a rectifier 2t, whose inputterminals are connected through a transformer 25 with one leg ofthe A.C. circuit to the lamps i3. rl"he four legs or resistances of the bridgemay have, for example, r1 at 400 ohms, r2 at 3.3 chris, 13 at 5@ ohmsand 14 at 5 ohms. Resistance 1'1 may be adjusted to obtain the desiredinitial unbalance of the bridge vso that the voltage impressed on coilv22 will be that required for limiting the voltage loutput of therectifier I to the proper value 'when lamps I3 are not used. Thedirection ci lcurrent iiow to coil 22 is represented arrows When one ormore lamps I3 are switched on, transformer -25 is excited and rectierimpresses a D. C. Voltage on resistance r4 in opposition to the voltageimpressed thereon by rectilier I4 so `that the voltage impressed on coilE2 is less than would exist if the lamps it were not burning. 'Thereforethe D. C. output Voltage of the rectier It Iis increased.

Si-nce transformer 25 is a current transformer,

the D. C. voltage output oi rectifier 2Q will be proportional to A. C.used by lamps E3. l`i"hereriore the amount of increase in D. C. outputVoltage of rectier it will be proportional to il. C. used by the lamps.

Referring to Fig. 2, curve I shows the relation voi actual D. C. outputVoltage to stack resistance required-tor regulation over the speed rangewhile the genera-tor is not supplying current to the 1am-ps I3.A-s-voltage climbs from zero to V3, the regulating resistance increasesto 1'3. With iurther increase in speed, the voltage doesv not in creasematerially above 'Vs since the stack resistance is increased 'fuit-herby increased magnetic pull of -coil 12E. 'When speed falls below that atwhich V3 was iirs-t attained the output voltage may fall `to V2 and theresistance of the stack will decrease to r2. When the speed decreasesstil-l further, the Aoutput voltage may decrease to V1 Aand :theresistance of the stack will be de- Let it lbe assumed that when thegenerator is able to produce, through the rectier lli, a D. C. outputvoltage V2, the generator A. -C. `output voltage -wlll he sufcient tomain- Ii stack resistance less than Curve 1110i Fig. 2 shows thecharacteristic of Vregi-ilation of -D. C. output'voltage when the lampsare drawing A. C. from the generator. Since voltage from rectier 24bucks voltage from rectier I4, the D. C. output voltage is greater thanthat which occurred at the corresponding speeds when regulation is thatindicated by curve I. The characteristic of the regulator is now suchthat D. C. voltage V2 can be maintained with stack resistance n' insteadof r2 as in the case of the characteristic represented by curve I. Thismeans the speed at which the generator can produce A. C. voltagesuicient to maintain the lamps I3 is less because the stack resistancehas been reduced to 1'1 so that eld excitation is greater than it wouldhave been if resistance 1'2A were existing as in the case of curve I.

These characteristics are inherent in a carbon pile regulator, therebeing a spring such as 2| which puts pressure on the stack and a magnetcoil such as 22 which takes off the pressure. Curve III of Fig. 3 showsthe relation of stack pressure to stack resistance. The pressure on thestack at any instance is equal to difference between the initial forceof spring 2| and the pull of the coil 22. The higher the voltageimpressed on coil 22, the lower the pressure on the stack. At regulatedvoltage, there is a balance between spring force and coil magneticforce; and stack pressure can decrease to Zero at high speed. Stackresistance is a function of the difference between the voltage at whichthe regulator is set and the actual voltage impressed on the coil 22.

Let the former voltage be VR and the latter V, then it follows thatcurve IV of Fig. 4 (which is similar to curve III of Fig. 3) representsthe relation between (Vie-V) and stack resistance. As (VR-V) decreasesstack resistance increases and vice versa. VR being a constant, as Vincreases (VR-V) decreases. Therefore as V increases, stack resistanceincreases according to curve I or II of Fig. 2.

Curve V of Fig. 5 shows the relation of D. C. output voltage V to speedwhen the regulator modier is not functioning and curve VI when themodier is functioning. At speed s2, the D. C. output voltage is V2 whenthe modier is not functioning. Speed s2 is the lowest generator speed atwhich the A. C. voltage will be suiiicient to maintain lamp I3 if themodiiier is not functioning. At a lower speed s1, the D. C. outputvoltage is V2 on curve VI when the modier is functioning by virtue ofturning on lamps I3. When the vehicle is being propelled with thetransmission in high, at a speed corresponding to which the generatorspeed is s1, the generator A. C. voltage would be insuliicient withoutthe modifier functioning to maintain operation of the uorescent lamps;but, with the modifier functioning, D. C. voltage V2 exists at speed s1and calls for lower resistance r1 as shown by curve II (Fig. 2) so thatthe A. C. voltage is suiiicient to maintain these lamps when vehiclespeed is that corresponding to generator speed s1 when the transmissionis in high.

While the embodiment of the present invention as herein disclosed,constitutes a preferred form, it is to be understood that other formsmight be adopted.

What is claimed is as follows:

1. A generating system comprising an A. C. generator driven at variablespeed and having a eld winding' excited by direct current, a deviceoperated by alternating current, means connected with the outputterminals of the generator for supplying A. C. to the device said meansincluding a device connecting switch, means supplying direct current tothe neld winding and including a rectifier having input terminalsconnected with the generator terminals and D. C. output terminalsconnected with the neld winding, means for regulating the D. C. outputof the rectifier and comprising a carbon pile regulator having a, stackin the circuit of the eld winding, a spring for applying pressure to thestack and an electromagnet opposing the spring and having a coilconnected with the D. C. output terminals of the rectiner, a Wheatstonebridge comprising four resistances and having end terminals connectedwith the rectier and intermediate terminals connected with the regulatorcoil, said resistances having values such that a voltage is impressed onthe regulator coil by the rectier, and means rendered eective when byclosure of said switch the device receives A. C. from the generator forimpressing upon one leg of the bridge a voltage bucking the voltageimpressed by the rectifier' thereby reducing excitation of the regulatormagnet and decreasing stack resistance and increasing A. C. outputvoltage.

2. A generating system comprising an A. C. generator driven at variablespeed and having a eld winding excited by direct current, a deviceoperated by alternating current, a Voltage transformer having a primarywinding connected with the generator terminals and a secondary winding,a switch connecting the secondary winding with the device, meanssupplying direct current to the eld winding and including a rectierhaving input terminals connected with the generator terminals and D. C.output terminals connected with the field winding, means for regulatingthe D. C. output of the rectifier and comprising a carbon pile regulatorhaving a stack in the circuit of the eld winding, a spring for applyingpressure to the stack and an electromagnet opposing the spring andhaving a coil connected with the D. C. output terminals of the rectier,a Wheatstone bridge comprising four resistances and having end terminalsconnected with the rectii'ier and intermediate terminals connected withthe regulator coil, said resistances having values such that a voltageis impressed on the regulator coil by the rectifier, a currenttransformer having a primary winding connected in series with a terminaiof the primary winding of the voltage transformer and a generatorterminal and having a secondary winding, a second rectifier having inputterminals connected with the secondary winding of the currenttransformer and output terminals connected with the ends of one leg ofthe bridge, whereby, when the device controlling switch is closed, thereis impressed upon said leg a voltage bucking the voltage impressed bythe rectiiier thereby reducing excitation of the regulator magnet anddecreasing stack resistance and increasing A. C. output voltage.

ROBERT J. CASSDDY.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,158,001 Neeley Oct. 26, 19152,010,571 Wagner Aug, 6, 1935 2,281,034 Geiselman Apr. 28, 1942

